JPH11174015A - Water content measurement device and sensor thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly output a water content of a uniformly mixed water-ink suspension over a wide water concentration range without using any logarithmic amplifier by comprising opposed two pole plates, providing at least one aperture, through which an object to be measured is introduced, in a housing, deciding an electrostatic capacity between the opposed two pole plates in relation to a substance existing between the pole plates. SOLUTION: A water content measurement device 10 is used for a uniformly mixed suspension. As a water sensor 20, an electrostatic capacity type sensor, through which flow of the suspension to be measured fed from a mixer can be passed, is desirable. the suspension is passed through between two pole plates 22 forming the electrostatic capacity sensor 20. Because an electrostatic capacity is directly decided on the basis of a dielectric constant of a substance existing between the pole plates 22, the electrostatic capacity of the sensor 22 is changed when a dielectric substance between the pole plates 22 is changed. In the suspension, a dielectric constant is varied according to water concentration, so that the water concentration can be measured between the two pole plates 22 on the basis of the electrostatic capacity of the sensor 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water measuring device for monitoring the water concentration of a water-ink suspension aqueous solution used in a printing press and a sensor therefor.

[0002]

2. Description of the Related Art Ink used in a lithographic printing press usually consists of two components, an ink and a humidifying solution. The humidifying solution is water with small amounts of additives that promote the humidification of the non-printing parts of the printing plate. Heretofore, the ink and the humidifying solution have been supplied through separate routes.

However, to simplify the printing press and reduce costs, a premixed suspension of ink and water (ie, a humidified solution) may be supplied to the printing press in a single pass. Since the amount of the suspension used in a unit time is small, the water-ink suspension aqueous solution is circulated through the system only by rubbing the ink train from the viewpoint of economical operation. The abraded suspension has 10-20% less water than the original. For optimal printing results, the suspension must maintain a suitable moisture concentration. This water concentration is usually 30 to 50%, depending on the ink composition. At the start of printing, new ink and water can be mixed in an appropriate ratio. However, as printing proceeds, the ratio of ink to water in the circulating suspension changes. When a new suspension is continuously replenished during the printing process, it is often necessary to continuously measure the water concentration in the suspension in real time.

[0004] Measuring instruments for measuring the concentration of a suspension by means of the insulating constant of the suspension are known. Some of these instruments use a Wheatstone bridge to measure the insulation constant (eg, US Pat. No. 4,048,844). Other instruments use an oscillator (eg, US Pat. No. 4,130,796) or a logic circuit (eg, US Pat. No. 4,399,404) with a peak detector. US Patent 4,559,4
No. 93 discloses a water concentration measuring device for a water-ink suspension. However, while the logic amplifier of the instrument described in the '493 patent excludes the region of 0-20% moisture, most printing uses a suspension of 20-50% moisture. Thus, the '493 patent describes, as a preferred embodiment, a logarithmic amplifier for linearizing the output of the sensor.

Further, the above-mentioned measuring instrument has another problem besides the expansion of the application range of the logarithmic amplifier. For example, in a certain measuring instrument, an electrode plate used for a capacitance sensor is deformed or displaced by pressure. When the electrode plate is deformed or displaced, the output fluctuates depending on the flow rate, and a measurement error occurs in the target variable, that is, the water concentration.

[0006] The output of a conventional capacitance sensor is affected by the component distribution in the suspension to be measured. For example, even if the water-ink suspension has exactly the same composition, it may have a different insulating constant depending on the distribution of the components. As an extreme example, when water and ink form a layer, even if the water-ink suspension has the same composition, the insulating constant will differ depending on the depth. For this issue, see Mougn
U.S. Pat. No. 4,916,490 to e) describes a mixture of water and oil as an example.

Further, in the conventional measuring device, the influence of the leakage electromagnetic field becomes a problem when performing a precise measurement.

[0008] It is an object of the present invention to overcome the above-mentioned problems of the prior art moisture meter and to disperse the moisture of a homogeneously mixed water-ink suspension over a wide moisture concentration range without using a logarithmic amplifier. An object of the present invention is to provide a moisture meter using a sensor capable of obtaining a linear output.

[0009]

SUMMARY OF THE INVENTION In one form of the invention, a moisture meter uses a capacitance sensor connected to an oscillator acting as a multivibrator. The suspension to be measured passes between two opposing electrode plates of the capacitance sensor whose capacitance changes according to the water concentration of the suspension. The output frequency of the oscillator changes depending on the capacitance of the sensor. The output frequency of the oscillator is converted into a signal corresponding to the water concentration of the suspension by a water concentration converter. The moisture concentration converter generates a moisture concentration signal according to a linear mapping function in which the voltage of the frequency-voltage converter falls linearly in inverse proportion to the increase in the moisture concentration.

In another important aspect of the present invention, there is provided a moisture meter as described above which has a linear mapping function in a moisture concentration range of 0 to 50%.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a moisture meter 10 of the present invention. The measuring device is particularly suitable for measuring the water concentration of a water-ink suspension used in a printing press. However, this measuring instrument 10
It is not limited to printing presses or specific suspension measurements. The use of the measuring device 10 is suitable for a lithographic printing machine,
The application is not limited to a specific printing machine. Rather, due to its nature, it can be applied to various uses within the scope of the present invention.

The moisture meter 10 is preferably used for a uniformly mixed suspension to avoid the above-mentioned problems of the conventional apparatus. The mechanism for uniformly mixing the suspension will be described later. The term “homogeneously mixed suspension” as used herein means a suspension in which each component is uniformly mixed throughout the entire liquid.

In order to detect the moisture concentration in the suspension to be measured, the moisture measuring device 10 is provided with a moisture sensor 20. As shown in FIG. 1, the moisture sensor 20 is a capacitance type,
It is desirable to pass the flow of the suspension to be measured sent from the mixer. Not all of the suspension sent from the mixer to the printer needs to pass through the sensor. Rather, a portion of the suspension in the system may be passed through the sensor as a sample. Further, the sensor 20 is desirably installed on the upstream side of the printing press, but may be installed in another place. For example, if the suspension is to be circulated, the sensor 20 can be located downstream of the printing press.

In any case, the suspension is passed between the two plates 22 forming the capacitance sensor 20. Since the capacitance is directly determined by the dielectric constant of the material between the plates 22, changing the dielectric material between the plates 22 will change the capacitance of the sensor 20. Since the dielectric constant of the suspension changes depending on the water concentration, the water concentration of the suspension is measured between the two electrode plates 22.
It can be measured by a capacitance of 20.

In order to monitor such a change in the capacitance of the sensor 20, the moisture meter 10 is provided with a frequency oscillator 40. The frequency of the frequency oscillator 40 changes according to the capacitance of the sensor 20, and the oscillator 40 emits a frequency signal inversely proportional to the capacitance of the sensor.

As shown in FIG. 1, the frequency signal output from the oscillator 40 is preferably encoded as a deviation signal via an RS-422 driver 46. This deviation signal is transmitted to the RS-422 receiver 47 via a standard twin-stranded cable 50. Receiver 47 uncodes the deviation signal and transmits the uncoded signal to frequency-to-voltage converter 60. As the name implies, the frequency-voltage converter 60 generates an output voltage proportional to the frequency of the frequency signal from the oscillator 40.
In a preferred embodiment, the input / output ratio of the frequency-to-voltage converter 60 is 20 KHz / volt.

In any case, as shown in FIG.
The output voltage of 60 passes through a normal low-pass filter 70
High frequency noise generated in the sensor 20 or the transmission line 50 is removed. The signal from which the noise has been removed is digitized by a normal analog-to-digital converter 80, converted into a water concentration by a water concentration converter 82, and the output is used to control the mixer.
That is, the moisture sensor 20, the oscillator 40, the RS-422 driver 46, the cable 50, the RS-422 receiver 47, the frequency-voltage converter 60,
The filter 70, the analog-to-digital converter 80, and the moisture concentration converter 82 can be connected to a mixer to form a feedback loop to adjust the moisture concentration in the measured suspension.

The use of such a feedback loop to adjust the water content of the suspension in the mixer is outside the scope of the present invention, and will not be described. However, any conventional mixer can be used within the scope of the present invention. For example, water or ink can be added from the mixer to the suspension of the entire process, or the mixer can control the supply of any or all of the components of the suspension.

FIGS. 2 and 3 show the details of the sensor 20. FIG. As shown in each figure, the sensor 20 has two metal plates 22. Although the shape and size of the metal plate are arbitrary, it is preferable that the metal plate 22 is a circular plate that is arranged in parallel at an interval. Preferably, the ratio of the diameter to the spacing of the disks 22 is between 12: 1 and 20: 1. As the disk, a metal plate such as a stainless steel plate or the like is preferably coated with a synthetic resin such as tetrafluoroethylene on the opposite surface. The synthetic resin coating insulates the disk 22 from the suspension to prevent corrosion of the disk. In addition, since a conductive substance is added to the suspension as a humidifier, this insulation is also necessary to prevent a leakage current between the disks 22.

Each disk 22 is preferably embedded and fixed in the side insulating material 24 so that the disks 22 are fixed at predetermined positions and do not move during use. As shown in FIG. 3, a space having the above-mentioned predetermined interval is formed between the disks 22 by the insulating material 24. Each disk 22 is fixed in place with an insulating cement 23 such as epoxy cement sold by Locite, and the side insulation 24 is made of a non-conductive material such as Delrin. desirable. The disk 22 is preferably installed in a metal housing 26 so as not to be affected by the leakage electromagnetic field. A space is formed in the housing 26 for holding the side insulating material 24 at a predetermined position. The housing 26 is provided with a fixing member 27 such as a bolt for fixing the sensor 20 at an appropriate position. It is desirable to use a gasket 28 to prevent liquid leakage from the housing 26.
As shown in FIG. 3, the housing 26 has two opposing side members, a top member, and a bottom member, which are bolts (not shown).
Assembled in the usual way. To monitor the change in capacitance between the disks 22, the housing 26 is provided with two opposing holes. A metal rod 30 surrounded by an insulating sleeve 32 is inserted and fixed in the two opposing holes. One end of each metal rod 30 is connected to each disk 22, and a connecting wire 34 is connected to the other end. Connection wire 34 (Fig. 1
Is connected to the oscillator box 36 containing the oscillator 40 and the RS-422 driver 46. As shown in FIG. 3, the oscillator box 36 has the wires 34 shortened and mounted on the housing 26 to reduce harmful capacitance.

As shown in FIG. 2, the housing 26 is preferably provided with two opposing openings 38 communicating with the gap between the disks 22. The water-ink suspension is pumped into the gap between the disks 22 through this opening 38. As described above, the capacitance of the sensor 20 changes in proportion to the dielectric constant of the suspension. As a result, the output frequency of the frequency-to-voltage converter 60 is linearly proportional to the water concentration of the uniformly mixed water-ink suspension in a water concentration range of 0-50%. Since this proportional relationship is linear, the logarithmic amplifier of the conventional measuring instrument is not required. As shown in FIG. 6, a linear relationship within a desired range is obtained.

The oscillator 40, RS-422 driver 46, connection cable 50, RS-422 receiver 47, frequency-to-voltage converter 60, and low-pass filter 70 circuits are illustrated in FIGS. These circuits are examples and various changes can be made within the scope of the invention.

As shown in FIG. 4, oscillator 40 preferably includes a conventional '555 timer 42 with a suitable bias circuit in the form of a voltage divider network 44. The timer 42 acts as a multivibrator having a divided network 44 and the sensor 20, and forms an RC circuit for determining a time constant. Specifically, as shown in FIG. 4, timer 42, split network 44, and capacitance sensor 20 are connected to a 5 volt power supply. When a voltage is supplied, as is well known, the capacitance sensor 20 is charged, and when a predetermined charge is charged in the sensor 20, the timer 42 outputs a pulse and the sensor 20 is discharged. Thus, the cycle of charging and discharging of the sensor 20 is repeated, and the timer 42 outputs a frequency signal determined by the time constant of the RC circuit. Since the resistance of the dividing network 44 is constant,
The time constant of the RC circuit changes according to the capacitance of the sensor 20. Therefore, the time constant of the RC circuit changes due to the capacitance of the sensor 20, which changes according to the dielectric constant of the suspension between the disks 22, and the output frequency of the timer changes. In a desirable mode, the output frequency of the timer 42 can be expressed by the following equation. F = 1.44 / (R ₁ + 2R ₂ ) C where F is the output frequency (Hz), and R ₁ and R ₂ are the dividing network 44
Is the capacitance (f) of the sensor 20.

The output frequency range of the timer 42 is 0 to 100 KHz.
It is desirable that Therefore, the sensor 20 has a capacitance of 150-350 pf for a uniformly mixed water-ink suspension.
It is desirable that it be designed so that Therefore, it is desirable to select each resistance of the dividing network 44 to be 47.6 to 100 KΩ. The sensor 20 and the dividing network 44 set in this way are
According to 0 to 100K for all assumed moisture concentrations
The time constant of the RC circuit from which the timer 42 output of Hz is obtained is set.

In order to connect the output of the timer 42 to the frequency-to-voltage converter 60 in a manner with little trouble or loss, as shown in FIGS. 4 and 5, an RS-422 driver 46 is used as a support circuit.
Normal two-stranded cable with cable and RS-422 receiver 47
50 is used. In a preferred embodiment, the RS-422 driver 46 receives the signal of the timer 42 and converts it into two identical signals at the same frequency as the output of the timer. As shown in FIG.
The two signals are 180 ° out of phase. The two signals formed by the RS-422 driver 46 are transmitted via the cable 50 to the RS-4
22 is transmitted to the receiver 47. The RS-422 receiver 47 regenerates from the two signals one signal which is substantially the same as the signal of the timer 42. In a preferred embodiment, the driver 46 and the receiver 47 use the SN75172 and SN75173 chips sold by Texas Instruments, respectively, but other chips can be used.

As shown in FIG. 5, the reconfigured timer 42
Is converted by a normal frequency-voltage converter 60 into a voltage signal proportional to the output frequency of the timer. As described above, the output range of the timer is desirably 0 to 100 KHz. It is desirable that the input / output ratio of the frequency-voltage converter 60 is 20 KHz / volt. With this frequency range and input / output ratio, the converter
The output voltage at 60 is in the range of 0-5 volts, which facilitates processing in the downstream analog-to-digital converter 80. As the converter 60, ADVFC32 sold as a part by Analog Devices, Inc. can be used, but other parts can also be used.

The frequency-to-voltage converter 60 can be adjusted to an appropriate operating range using a conventional bias circuit, as shown in FIG. As shown in FIG. 5, it is desirable that a changeable resistor 62 is incorporated in the bias circuit as a calibration means of the converter 60.

As described above, with reference to FIG.
Is preferably passed through a low-pass filter 70 before being transmitted to the analog-to-digital converter 80 and the moisture concentration converter 82. As shown in FIG.
As the device, a normal device having a resistor 72 and a capacitor 74 can be used.

In a preferred embodiment, the water concentration converter 82
Has a microprocessor programmed in a conventional manner to have a linear mapping function as shown in FIG. The water concentration of the uniformly mixed suspension is 0 to
The mapping function is linear over a 50% range. The mapping function is represented by the following equation. Moisture concentration = XY * V where X and Y are constants, and V is a frequency-voltage converter.
60 output voltages. The constants X and Y relate to the composition of the additive and the ink in the suspension and their ratio. The constants X and Y can be determined by an empirical analysis technique. 1
As an example, as shown in FIG. 6, X = 60.94 and Y = 1
5.12 is for a uniformly mixed black ink sold by US Ink Company.

As shown in FIG. 6, the mapping function usually has a downward slope in which the output voltage of the frequency-to-voltage converter 60 decreases as the moisture concentration increases.

In the present embodiment, a microprocessor programmed in the moisture concentration converter 82 is used, but other devices can be used within the scope of the present invention. For example, a voltage division circuit network or an addition circuit using electric wiring can be used. Similarly, in the present embodiment, the analog-to-digital converter 80 is used to digitize the output of the converter 60.
However, the analog-to-digital converter 80 can be omitted and the moisture concentration converter 82 can be processed in analog.

As mentioned above, it is desirable to use a uniformly mixed ink-water suspension. A new and improved mixer for obtaining such a homogeneously mixed suspension is described below. This mixer is disclosed in U.S. patent application Ser.
22,004.

As shown in FIG. 7 and FIG.
6 has a first circular horizontal wall 164, a height of 21.0 cm and an inner diameter of about
It has a container 163 in which a cylindrical upper chamber 168 is formed by a cylindrical upper vertical wall 166 of 17.8 cm.

The first horizontal wall 164 has a hole 170 with a diameter of about 6.4 cm.
Is provided. Below the first horizontal wall 164 of the container 163, a cylindrical lower vertical wall 172 having a diameter of about 18.3 cm is provided. The first horizontal wall 164, the cylindrical lower vertical wall 172, and the second circular horizontal wall 174 form a cylindrical lower chamber 176. A gear pump 180 having a square opening 178 of about 8 cm square provided on the second circular horizontal wall 174 is mounted, and driven by a motor (not shown) to discharge the water-ink suspension from the lower chamber 176.

A cup-shaped external stator (stationary body) 182 is attached to the first horizontal wall 164, and its cylindrical wall 186 has a thickness of about 4.8 mm and 24 vertical holes 184 formed at equal intervals. A cup-shaped internal stator 188 is fixed to the external stator 182, and its cylindrical wall 192 has a thickness of about 4 mm and 16 vertical holes 190 formed at equal intervals. Vertical holes 184 and 190
Has a height of about 15.9mm and a width of about 3.4mm.

A high-speed motor 194 is provided above the upper chamber 168, and drives the motor shaft 196 to rotate clockwise when viewed from above, as indicated by an arrow 198. The propeller 100 is mounted on the motor shaft 196, and each of the three propeller blades 102 provided at an equal angular interval of 120 ° has approximately 20 degrees with respect to the horizontal direction so that the leading edge 104 is above the trailing edge 106.ピ ッ チ pitch is attached. The propeller 100 has a wing diameter of about 12.7 cm, and the upper chamber 1
Within 68, above the first horizontal wall 164, it is attached to the motor shaft 196 at a height equal to half the blade diameter and equal to the blade diameter.

At the lower end of the motor shaft 196, the rotor 108 (particularly FIG.
And FIG. 10). The rotor 108 has three horizontal blades 110 provided at equal angular intervals of 120 °. Each wing 110 has internal teeth 112 and external teeth 11 extending downward.
4 are provided. Each internal tooth 112 is connected to the internal stator wall 19.
Inside 2, the external teeth 114 are between the inner stator wall 192 and the outer stator wall 186. There is a relatively small spacing of about 0.4 mm between each tooth 112,114 and the stator walls 186,192.

During operation, the motor rotates at about 500 to 4000 revolutions per minute, and the motor shaft 196, the rotor 108, and the propeller 10
0 rotates at the same speed as the motor 194. Due to the pitch of the propeller wings 102, the rotation of the propeller 100
The ink and the raw material solution in the upper chamber 168 are mixed and simultaneously swept downward toward the rotor 108. Rotation of the rotor 108 causes shearing of the ink and solution between the rotor teeth 112, 114 and the inner and outer stator walls 192, 186.
Due to this shearing, the liquid is dispersed in the vertical holes 190, 184 of the inner and outer stators 192, 186 and flows into the lower chamber 176 as a finely dispersed water-ink suspension. The water-ink suspension is then delivered by a gear pump 180 to a supply tube to a printing press.

The propeller 100 premixes the ink and the raw material solution so that the raw material solution added to the upper chamber 164 stagnates on the upper surface of the ink, thereby preventing the formation of a water-ink suspension having a predetermined moisture concentration. Not to be. Propeller 100
The formation of a gap in the upper part of the rotor 108 is prevented so that the flow of ink and liquid into the lower chamber 176 is not hindered.

In short, as described above, according to the measuring apparatus of the present invention, a linear output is obtained when the water concentration in the uniformly mixed water-ink suspension is in the range of 0 to 50%, and the logarithmic amplifier is obtained. Is unnecessary. In particular, in this moisture meter, the water concentration in the uniformly mixed water-ink suspension is 0 to 0.
A linear output is obtained at 50%, the normal use range of most water-ink suspensions. Further, it can be seen that a sensor used in the above-described type of moisture concentration measuring device is also disclosed.

Further, while the present invention has been described with reference to the above specific embodiments, it is not limited thereto. Rather, the wording of the subject matter recited in the claims, and all modifications and forms falling within the equivalent range thereof, fall within the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a flow sheet of the moisture meter of the present invention.

FIG. 2 is a plan view of a sensor used in the moisture meter of the present invention.

FIG. 3 is a sectional view of the sensor taken along line 3-3 in FIG. 2;

FIG. 4 is a circuit diagram of a driver circuit of the moisture meter shown in FIG.

FIG. 5 is a circuit diagram of a receiver circuit of the moisture meter shown in FIG.

FIG. 6 is an output example of the sensor shown in FIGS. 2 and 3;

FIG. 7 is a partially broken side view of the mixing and dispersing device.

8 is a plan view of a rotor, an inner stator, and an outer stator of the mixing and dispersing device shown in FIG.

FIG. 9 is a partial side view of the rotor, inner stator, and outer stator taken along line 9-9 of FIG.

FIG. 10 is a bottom view of the rotor of the mixing and dispersing device shown in FIG. 7;

[Explanation of symbols]

 10 ・ ・ ・ Moisture measuring device 20 ・ ・ ・ Moisture sensor 22 ・ ・ ・ Plate (disc) 24 ・ ・ ・ Side insulation 26 ・ ・ ・ Housing 36 ・ ・ ・ Oscillator box 38 ・ ・ ・ Opening 40 ・ ・ ・Frequency oscillator 46 ・ ・ ・ Driver 47 ・ ・ ・ Receiver 50 ・ ・ ・ Cable 60 ・ ・ ・ Frequency-voltage converter 70 ・ ・ ・ Low-pass filter 80 ・ ・ ・ Analog-digital converter 82 ・ ・ ・ Moisture concentration converter 100 ・ ・ ・ Propeller 108 ・ ・ ・ Rotor 156 ・ ・ ・ Mixer / disperser 180 ・ ・ ・ Gear pump

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Thomas W. Inventor. Orzechowski United States 60462 Illinois Orland Park Coventry Court 15257 (72) Inventor Shen-Mont Chow United States 60559 Illinois Westmont S.S. Wilmette 827

Claims (24)

[Claims] 1. A capacitance sensor, comprising: a housing forming a first space; a side insulating material forming a second space in the first space; and a side insulating material forming a predetermined space in the second space. And the housing has at least one opening for introducing an object to be measured, and the capacitance of the two opposing electrode plates is present therebetween. An electrostatic capacitance sensor characterized by being determined in relation to a substance. 2. The sensor according to claim 1, wherein the housing is made of metal that shields the two electrode plates from an external electromagnetic field. 3. The sensor according to claim 1, wherein the two electrode plates are firmly fixed to a side surface insulating material. 4. The two electrode plates are made of metal and have opposing surfaces that determine the distance between each other, and each opposing surface is coated with a synthetic resin for corrosion prevention and current leakage prevention. The sensor according to claim 1. 5. The sensor according to claim 1, wherein the two opposing electrode plates are connected to a multivibrator. 6. The sensor according to claim 5, wherein the two opposite plates form a capacitor that determines the output frequency of the multivibrator in the RC circuit. 7. The sensor according to claim 5, wherein the multivibrator is mounted on the housing. 8. The sensor according to claim 6, wherein the substance to be measured is a uniform suspension containing water, and the output frequency of the multivibrator changes linearly within a water concentration range of 0 to 50%. 9. The two opposing electrode plates are disks of the same diameter arranged in parallel, and the ratio between the diameter of the disk and the distance between the electrode plates is 12: 1 to 20: 1. The sensor according to claim 1. 10. A moisture concentration measuring device for monitoring moisture in a uniform suspension, comprising: a multivibrator whose output frequency is determined by a time constant of an RC circuit; a static vibrator which varies according to the moisture concentration in the suspension. Capacitance sensor in which the capacitance changes, the RC time constant changes according to the capacitance of the sensor, and the frequency of the multivibrator changes linearly according to the moisture concentration in the moisture concentration range of 0 to 50% A converter connected to the multivibrator and outputting a moisture concentration according to a mapping function. 11. The measuring device according to claim 10, wherein the mapping function is a downward slope in which the output frequency of the multivibrator decreases according to the moisture concentration detected by the sensor. 12. The mapping function for the water concentration is linear when the water concentration is in the range of 0 to 50%.
The measuring device as described. 13. The capacitance sensor is fixed to a housing having a first space; a side-surface insulating material forming a second space in the first space; and an equi-spaced parallel to the side-surface insulating material in the second space. 11. The measuring device according to claim 10, further comprising two electrodes, wherein the housing has at least one opening for introducing the suspension to be measured between the two electrodes. 14. The measuring device according to claim 10, wherein the converter is a frequency-voltage converter that converts an output frequency of a multivibrator into a voltage, and the moisture concentration converter performs the mapping function. 15. The measuring device according to claim 14, wherein the moisture concentration converter is constituted by a microprocessor. 16. The measuring device according to claim 15, wherein an analog-digital converter is connected between the frequency-voltage converter and the microprocessor. 17. The mapping function is as follows: when X and Y are constants related to the suspension, and V is the voltage output of the frequency-voltage converter, the water concentration is represented by X− (Y * V). The measuring device according to claim 14. 18. The measuring apparatus according to claim 17, wherein said X and Y are determined by an analysis method. 19. The measuring device according to claim 10, wherein the multivibrator is connected to the converter via a two-stranded cable. 20. The measuring apparatus according to claim 19, further comprising an RS-422 driver and an RS-422 receiver connected to both ends of a two-stranded cable for transmitting an output frequency of the multivibrator as a digital signal. . 21. A device for monitoring the concentration of water in a homogeneously mixed suspension, the capacitor having two coated metal surfaces, the metal surfaces being shielded from an external electromagnetic field by a metal housing. At least two openings for delivering a homogeneously mixed suspension between the two metal surfaces of the condenser; the vibration frequency depends on the moisture concentration in the uniform suspension between the two metal surfaces;
An oscillating circuit using a condenser; and a conversion means for converting the frequency of the oscillating circuit into a uniform moisture concentration in the suspension, having a linear function of a downward slope whose frequency decreases linearly with an increase in the moisture concentration. A moisture concentration monitoring device comprising: 22. A frequency-to-voltage converter for converting a frequency signal to an analog voltage signal, an analog-to-digital converter for converting an analog voltage signal to a digital value, and water in the suspension from the digital value. 22. The monitoring device according to claim 21, further comprising a digital computer for determining the concentration. 23. The monitoring device according to claim 21, wherein the conversion unit is separated from the vibration circuit, and the vibration frequency is transmitted as a deviation signal to the conversion unit via a two-stranded cable. 24. The monitoring function according to claim 1, wherein at least the water concentration is zero.
22. The monitoring device of claim 21, wherein the monitoring device is linear in the range of ~ 50%.